Some vehicles such as automobiles are known to be equipped with a parking assist device. The parking assist device assists the vehicle when the vehicle is pulled into (is parked in) a certain parking area and pulled out of (starts from) the parking area.
To pull a vehicle into or out of a parking area, the parking assist device operates the steerable wheels of the vehicle through automatic control of the steering device, instead of using steering operation by the driver. Specifically, the vehicle is pulled into the parking area through automatic pulling-in control by which the steering device is automatically operated. The vehicle is pulled out of the parking area through automatic pulling-out control by which the steering device is automatically operated. Through such automatic pulling-in and pulling-out controls, the steerable wheels are operated to pull the vehicle into or out of the parking area without steering operation by the driver. In this manner, the vehicle is assisted to be pulled into or out of the parking area.
When a vehicle is assisted to be pulled into or out of a parking area by a parking assist device, the steerable wheels are operated solely by the power of the actuator, such as a motor, of the steering device through the automatic pulling-in or pulling-out control without depending on any steering operation by the driver. This increases the load acting on the steering device when the automatic pulling-in or pulling-out control is performed compared to usual times. The temperature of the steering device thus tends to increase. As a result, in a vehicle having such a parking assist device, the parking assist device must have improved heat resistance.
In this regard, Patent Document 1 describes a configuration in which automatic pulling-in control is prohibited from starting if the temperature of the steering device is higher than the maximum value of a first temperature range. As a result, even if the temperature of the steering device increases after the automatic pulling-in control is started, the temperature of the steering device is maintained at a sufficiently low value. This restrains cost increase. The maximum value of the first temperature range may be set to a high value such that the condition for executing the automatic pulling-in control is relaxed to increase the execution frequency of the automatic pulling-in control.